An elevator comprises an elevator car, lifting machinery, ropes, and a counterweight. The elevator car is supported on a transport frame being formed by a sling or a car frame. The sling surrounds the elevator car. The lifting machinery moves the car upwards and downwards in a vertically extending elevator shaft. The sling and thereby also the elevator car are carried by the ropes, which connect the elevator car to the counterweight. The sling is further supported with gliding means at guide rails extending in the vertical direction in the elevator shaft. The gliding means can comprise rolls rolling on the guide rails or gliding shoes gliding on the guide rails when the elevator car is moving upwards and downwards in the elevator shaft. The guide rails are supported with fastening means on the side wall structures of the elevator shaft. The gliding means engaging with the guide rails keep the elevator car in position in the horizontal plane when the elevator car moves upwards and downwards in the elevator shaft. The counterweight is supported in a corresponding way on guide rails supported with fastening means on the wall structure of the elevator shaft. The elevator car transports people and/or goods between the landings in the building. The elevator shaft can be formed so that one or several of the side walls are formed of solid walls and/or so that one or several of the side walls are formed of an open steel structure.
The guide rails are formed of guide rail elements of a certain length. The guide rail elements are connected in the installation phase end-on-end one after the other in the elevator shaft. The guide rails are attached to the walls of the elevator shaft with fastening means at fastening points along the height of the guide rails.
WO publication 2007/135228 discloses a method for installing the guide rails of an elevator. In the first phase a first pair of opposite car guide rail elements is installed starting from the bottom of the shaft. In the second phase a second pair of opposite car guide rails is installed end-on-end with the first pair of opposite car guide rails. The process is continued until all the pairs of opposite car guide rails have been installed. The counterweight guide rails are installed in a corresponding manner. A laser transmitter is used in connection with each guide rail to align the guide rail in the vertical direction. A self-directional laser could be used, which automatically directs the laser beam vertically upwards. The laser transmitters are first positioned at the bottom of the shaft when the lowermost section of guide rails is installed. An alignment appliance provided with an alignment element is supported on each guide rail at each position where the alignment of the guide rail is to be done. The laser beam hits the alignment element, whereby the guide rail can be aligned so that the hitting point of the laser beam is in the middle of the alignment element. The laser transmitters are moved stepwise upwards for alignment of the next section of guide rails.
WO publication 2014/053184 discloses a guide rail straightness measuring system for elevator installations. The measuring system comprises at least one plumb line mounted vertically in the elevator shaft adjacent to the guide rail and at least one sensor arrangement to be mounted on a carrier to travel vertically along the guide rail. The sensor arrangement comprises a frame, at least one guide shoe connected to the frame for sliding or rolling along the guide surface of the guide rail, a bias means for placing and biasing the frame against the guide surface, and at least one sensor means for sensing the position of the plumb line with respect to the frame.